CP12 with 2 Appliances is £85+VAT. Additional Appliance is £25/each
CP12 and Boiler Service is £120+VAT
Usually, when an estate agent tells me they can get it cheaper, I try and inform and educate them. I try to explain the time it takes including travel time and then get them to understand they will be getting a rushed botched job. I always try to leave the conversation along the lines of "when it all goes wrong, you will get in trouble".
Some listen, some don't.
Some want to do their jobs to the letter of the law (yay!). Some are trying to make the most money (understandable). Some are afraid to tell landlords that stuff is expensive and costs money.
I worked for a company years ago that did gas checks cheaper the more the estate agents had. They used it as a way in and to get the remedial work.