No service for ages

Hi

I currently own an iPhone 5c and I'm on EE. Recently (last 3 days) my phone has been saying no service. I thought that i just wasn't connected or it was down for a few minutes. Then about 3 hours later I still didn't have service so I asked my mom who is also on EE if she had service and she did. I waited another couple of hours and it still said no service.

I then looked on the internet and it said to check the postcode thing and if it should work and I did and it said that I should have signal. I then turned my phone onto airplane mode and waited a few seconds then turned it off and it still said searching. I thought that in a couple of seconds it would find signal but it didn't. I waited an hour and it still said searching so I turned my phone off by holding the power button down then swiping then I turned it back on and it still said searching.

The next day I took the sim out and put it back in and it had signal ( keep reading) this lasted a couple of hours then it went off again and I have done this 2 times and it keeps doing the same.

I want to take it down to my carrier or apple but I'm worried they will charge me loads and I'm only 14. I'm going on holiday this Saturday and I need signal but my mom and dad are at work until Friday so I won't have time to go down and get it checked and I'm not sure what to do.

Any suggestions?

Thanks