The cowboys have now posted their response, and state that according to the manufacturers instructions and an independent report (not provided to me) the two adhesives did not need primer (BAL White Star and Topps powder adhesive applied on newly skimmed walls, very smooth). That disagrees with the data sheets I read online. They also claimed to have refunded all but materials costs, which is untrue. And of course they inflate materials costs by quoting recommended retail price, ignoring their trade discounts.
They also claim to have been polite, clean and tidy, but using my unused brand new fridge to store their food items, leaving the soil pipe improperly plugged so that sewage fumes filled the house and using screws to seal shut my garage without my knowledge is neither polite, clean nor tidy.
Someone might come to the conclusion that they are completely in the right. The problem is that the customer posts a review first. Then the trade gets to reply, and they can then say whatever they want to make it sound like the customer is at fault. The key problem is that CheckATrade is paid for by the trades. So it is biased in their favour. These people had two weeks to formulate a response due to my review appearing, then being removed for two weeks.
I will complain to CheckATrade about the inaccuracies in their online response. I will not hold my breath.