There’s an often overlooked aspect of business when it comes to customer service - the pickle principle - and the OP needs to apply it here.
What is more important to your business, saving on a few pence of tissue or having the customers come to your shop. A tea towel is a tea towel is a tea towel. You might have great one off designs, so does notonthehighstreet and dozens of other places on the internet and amazon/John Lewis do a great range of tea towels that are no doubt a lot cheaper than yours.
Customers go to boutique shops knowing that they’ll be paying a bit more but expect more in return or they’ll buy off the internet. That’s fundamental to surviving in modern business. Complaining that they want the items wrapped for free is leading down a slippery slope.
The Pickle Principle is taught in a lot of blue chip companies and was created by the owner of a hamburger restaurant in the states when he got the following letter:
“Dear Mr Farrell,
I’ve been coming to your restaurant for over three years. I always order a #2 hamburger and a chocolate shake. I always ask for an extra pickle and I always get one. Mind you, this has been going on once or twice a week for three years.
I came into your restaurant the other day and I ordered my usual #2 hamburger and a chocolate shake. I asked the young waitress for an extra pickle. I believe she was new because I hadn’t seen her before. She said, “Sir, I will sell you a side of pickles for $1.25.” I told her, “No, I just want one extra slice of pickle. I always ask for it and they always give it to me. Go ask your manager.”
She went away and came back after speaking to the manager. The waitress looked me in the eye and said, “I’ll sell you a pickle for a nickel.” Mr Farrell, I told her what to do with her pickle, hamburger and milkshake. I’m not coming back to your restaurant if that’s the way you’re going to run it”
A slice of pickle that cost cents to the restaurant lost them a customer.
He’s built a whole consulting business around this - PicklePrinciple and I highly recommend the OP buys his book and takes the time to read it.
And next time a customer asks you to wrap something they’ve bought from you - give ‘em the pickle