I once had a customer who said we stained the chrome in her electric fire and the front of her video recorder with carpet cleaning fluid.
I took the fluid in powdered form and mixed it with a small amount of water, to make a much stronger solution.
I told the customer if this solution now stained the fire and video I would replace them.
If it did not she should apologise
She did apologise.
In your case, I'd do the same with the taps, except if you are right, she should get herself a new cleaner.
What next, stains to the carpet, missing Rolex.
Regards Graham