They say that Colman's made their profit from the mustard left on the plate and I guess tile manufacturers make theirs's from the tiles we keep 'in case'. In the UK I usually had about a dozen but here I would have a lot more. I also noticed that cabinets (kitchens, bathrooms) and bathroom fittings (loo roll holders, towel rails etc.) sometimes are glued to the walls, not screwed - if they have to come off they take the (broken) tiles with them! One option for a small area is to try to insert different tiles and explain it as an artistic effect!
It would not be of much use to keep spare tiles to replace ones that are faulty especially if there is a few to be fixed, that would suggest the whole floor is suspect? when you chip away the broken parts of the faulty one the next tile to that will likely come loose and usually there are 4 tiles surrounding the faulty one, I know this as I have tried it and failed and had to replace the whole floor.
Hope I don't have to replace all my tiles down stairs, a few have popped and the area is 150 sqms (open plan) I'm going to leave it for now and wait until more have popped, save me from buying a jack-hammer lol.
It has already been said here: do not use cement mortar alone for a Tile adhesive unless it has an admix applied to it, I do not understand why you would repeat the drivel told to you by a Philippine Builder, virtually none of them have any formal training, if you believe all you hear you will eat all you see, an old Scottish saying and very true in your example above.
Sorry you couldn't replace a loose tile and destroyed the whole floor. If you run into that problem again let me know I can hook you up with a Pinoy builder that can teach you how to do the job.
Not for one moment do I believe a Pinoy Builder can do any better than myself, no way that is ever going to happen, in my case the floor was so bad I had the rest of the tiles up before the end of the day, (this was in the UK and the tiles were on a wooden floor) it was a bathroom so a small area. Dave I know you are trying to help here and thank you, but to recommend a Pinoy builder to me is like flashing a Red rag at a Bull. I cannot help for thinking that anyone here on this site that gives a recommendation for a Local builder or repeats advice coming from them is likely to have little knowledge of building in general. I Know you may be thinking I am prejudiced Scotsman, you have had much to say about us before haha, But I will have you know we are the least prejudiced race in the world, we HATE everyone and we don't even like other Scotsmen that much.
I do know a Filipino tile layer whom is also generally a Foreman in total house builds. He has tiled over 60 homes and also for many Foreigners. Generally he is sought after so I can provide a contact to any Member that does inquire via messaging me. Only down-side is he may be more than 4 0r 500 peso per day. He did all my Homes and one is 7 years old. Great work, all is solid!!