I am a sole trader of a small business that has been running for 10 years. I specialise in tiling but can tackle almost any handyman work including carpentry, decorating, general maintenance, fencing and bespoke garden gates.
My rates are very reasonable and I can supply dozens of references.
I am an engineer by trade but enjoy most aspects of handiwork. My business has been trading for the past 10 years doing this type of work. I am a member of another website advertising my trade but as with everything these days, work can be scarce.
in my experience this is extremely unusual. i personally do not charge a call out fee and more than likely would have had a part with me, or indeed would have been able to source on the same day. i make it part of my quote to state there will be no call out charge and if it's a simple job repair it then for more of a tip than a cost.
The main benefit is that it is able to be cleaned underneath as long as it's mounted securely on a solid wall.
Sounds like a leak from somewhere above.
Usually from 6pm but not everyone charges a call out charge. check with them first.
It is perfectly acceptable to tile over tiles but it takes much longer for the adhesive to cure. also be aware of the fact that you will reduce the size of the room by about 10mm on each re-tiled wall.