If you is receive bad posts on your social channels, have one or two of your loyal clients (brand advocates) respond to those messages with positive feedback. Most often people just want to be heard. Brand advocates are a more trusted source than only yourself responding. You do need to respond also, with customer service in mind, and do what you can to make that customer happy.
Build you content with positive messages and engage with your followers who leave comments on your social media channels. It’s okay to include clean humour into your weekly messages. By engaging with your followers it shows there is a real person behind your social media channels, not a bot auto-posting corporate messages—your followers will feel like they know and trust you before requesting your services.