Is this trademark too descriptive? Can they stop me using the phrase when describing goods and services offered by my business?

I own the website www.printypets.com. I recently received an email from the owner of the trademark “print your pet”. I was using an image in an advertisement that used the phrase “print your pet on a blanket”. They demanded I take it down and asked for my details so their lawyer could send a letter of demands. I don’t know how to respond. I am simply describing the service offered on my website. Other website do the same thing: • www.mypetprints.co • www.petcanva.com • www.popyourpup.com • www.ilovepaws.com And many more I do not see how I am not allowed to use “print your pet” when used in a larger phrase describing some of our goods and services. I’m in no way trying to confuse people or impersonate the Print Your Pet website at all. I’m just…