Son's birthday ruined

It was my son's birthday and I went Zevenwacht mall spur. We ordered food and all went well till it was time for them to sing for my son. We waited while they were singing for other kids. After sometime the waiter came to inform us that they were offline so they wont sing for him... no apology. We decided we were going to pay and I asked the waiter to use his voucher for him and I was told there's no voucher. I asked the waiter to ask his manager as I could see he was new so he came back to tell us that the manager said I should call customer service. I took out my phone snd when I was about to dial, the waiter told their customer care is closed. So I asked him what is the solution, he said he will bring the machine for me to pay. He then informed us that they were back online so they will sing for my son so we waited for over 30 minutes till we realised it was not happening so we stood up and the waiter brought the machine and we paid. On our way out my son asked "mommy why did they not sing for me but all the other kids were sang for" I was very disturbed because it was my idea to go to Spur because of all the extra things you do for kids to feel special