public async Task UnsubscribeFromNewsletter()
        {
            if (!await CheckIfAdminInGroups())
            {
                return;
            }

            if (MessageCommand.Parameters.Count != 1)
            {
                await ReplyTextMessageAsync("Usage:\n/unsubscribe <newsletter>");
            }
            var newsletterKey = MessageCommand.Parameters[0];

            var newsletters = await _newsletterService.GetNewslettersAsync();

            if (newsletters.Any(n => n.Key == newsletterKey))
            {
                if (await _newsletterService.IsChatSubscribedToNewsletterAsync(newsletterKey, TelegramChat !.Id))
                {
                    var result = await _newsletterService.SubscribeChatAsync(newsletterKey, TelegramChat.Id);

                    if (result)
                    {
                        await ReplyTextMessageAsync(
                            $"Successfully unsubscribed from the {newsletterKey} newsletter");
                    }
                    else
                    {
                        await ReplyTextMessageAsync(
                            "Can't unsubscribe from newsletter");
                    }
                }
            }
            else
            {
                await ReplyTextMessageAsync(
                    $"The newsletter {newsletterKey} doesn't exist.");
            }
        }