I’m not happy. I nearly completed level 19 Rescue centre and Iv have sent £16 buying diamond’s..

I’m not happy. I nearly completed level 19 Rescue centre and Iv have sent £16 buying diamond’s to complete before it runs out. I was one away from finishing leaving 19. Just went back on to complete it and I have to start level 19 all over again. I have been playing this game from when it first started and have spent money and time on the game. My four year old grandson love playing it so please could you sort out what went wrong. Thank you