Shift swap done and then shift removed

I work as a cashier. I wanted to perform a shift swap but could not do so on the app. I went to the front end coach to get my shift swapped with other associate who was willing to swap her shift with me. Went to the Coach on Friday and she said she will do it later. She did not do it. Reminded her on Sunday and she said she can't do it unless the other person is willing. Had the Coach talk with the other associate to confirm that she was willing to swap. The Coach said she will do it when she has time. Now mind you this was for Tuesday shift and she was in no hurry to do it on Sunday. Then again went to her today Monday three times because this was a valid request. Took about three tries today and an hour of our time for her to finally swap our shift in the system. I have no idea why she was so against the swap. Everyone does it and its completely valid as long as two parties agree.

1. I came home two hours later and my swapped shift was gone from the system !! That shift was for tomorrow.

2. My assigned hours on Thursday was also reduced to half !!?? How and Why?? She had done this once in the past as well and said its the management cutting hours. Just my hours ? Because all other part time associates had their hours intact. Can I ask for proof that they indeed cut everyone's hours ?

3. The person I swapped my shift with still has her shift but my shift for tomorrow is gone. Why would she do that?

I got such a bad headache because of the effort it took for such a small request. This is mental harassment. Any request we cashiers have needs to be taken to the front end coach and she never listens. The Coach is 32 y/o Female who has plenty of time to talk with young boys her age but no time to listen to your concerns? People lead is useless.

My question is can I find out who took it out from the system? Why did my hours change? Was it just a glitch or did she purposefully do this ?

Should I go to store manager for this. I think he is the only one who will listen to me but I am apprehensive about it.

Please guide.