Excerpt from the main Bot class; for complete code, please refer to CognitiveRocket repo.

VABot.cs

        private async Task ProcessVABotAsync(ITurnContext<Microsoft.Bot.Schema.IMessageActivity> turnContext, CancellationToken cancellationToken)
        {
            var token = await _botServices.VABotService.GetTokenAsync();

            using (var directLineClient = new DirectLineClient(token))
            {
                var conversation = await directLineClient.Conversations.StartConversationAsync();
                var conversationtId = conversation.ConversationId;

                var response = await directLineClient.Conversations.PostActivityAsync(conversationtId, new Microsoft.Bot.Connector.DirectLine.Activity()
                {
                    Type = Microsoft.Bot.Connector.DirectLine.ActivityTypes.Message,
                    From = new Microsoft.Bot.Connector.DirectLine.ChannelAccount { Id = "userId", Name = "userName" },
                    Text = turnContext.Activity.Text,
                    ChannelData = JObject.FromObject(_botServices.VABotService.ChannelData),
                    TextFormat = "plain",
                    Locale = "en-Us",
                });

                Thread.Sleep(4000);

                var activities = await GetActivitiesAsync(directLineClient, conversationtId, _botServices.VABotService.BotName);

                var activity = turnContext.Activity as Microsoft.Bot.Schema.Activity;

                await turnContext.SendActivitiesAsync(
                           activities
                           .Select(message =>
                           {
                               var reply = activity.CreateReply(message.Text);
                               reply.Attachments = message?.Attachments?.Select(a => new Microsoft.Bot.Schema.Attachment()
                               {
                                   Content = a.Content,
                                   ContentType = a.ContentType,
                                   ContentUrl = a.ContentUrl
                               }).ToList();

                               reply.SuggestedActions = new Microsoft.Bot.Schema.SuggestedActions()
                               {
                                   Actions = message?.SuggestedActions?.Actions?.Select(a => new Microsoft.Bot.Schema.CardAction()
                                   {
                                       Title = a.Title,
                                       Value = a.Value,
                                       Type = a.Type,
                                       Image = a.Image
                                   }).ToList(),
                               };

                               return reply;
                           })
                           .ToArray());
            }
        }

        private async Task<List<Microsoft.Bot.Connector.DirectLine.Activity>> GetActivitiesAsync(DirectLineClient directLineClient, string conversationtId, string botName)
        {
            ActivitySet response = null;
            List<Microsoft.Bot.Connector.DirectLine.Activity> result = new List<Microsoft.Bot.Connector.DirectLine.Activity>();
            string watermark = null;

            do
            {
                response = await directLineClient.Conversations.GetActivitiesAsync(conversationtId, watermark);
                watermark = response.Watermark;

                result = response?.Activities?.Where(x =>
                  x.Type == Microsoft.Bot.Connector.DirectLine.ActivityTypes.Message &&
                    string.Equals(x.From.Name, botName, StringComparison.Ordinal)).ToList();

                if (result != null && result.Any())
                { return result; }

                Thread.Sleep(1000);
            } while (response.Activities.Any());

            return result;
        }