Well it;s your own fault! LMAO Not really, it is she who is responsible for the bill, not you. After all she has to become responsible at some point and the best way is to start learning about the value of money
You could probably get a free sim card? o2, T-mobile, orange etc will all have them. After she has paid off her �300 she can then do chores to pay for the PAYG perhaps? Or, if you give her pocket money, maybe up her allowance for a monthly amount out of which she must pay for the phone? I ended up doing that with my daughter after it started to cost me �20 a week to top her phone up. Oh there were whinges and whines, but I stuck to my guns and she learnt a good lesson :)
Can I just make one comment about her punishment?
Now, I know what she did was wrong, totally and is going to cost �300 but, I feel the punishment is just a little to harsh. In effect you have punished her 5 times for one offence - if you see what I mean. (This is a big thing for me, sorry. One punishment per offence) Yes, absolutely remove her phone and she must of course pay back the �300 by doing chores etc but I feel taking away the holiday is just a little to harsh. I know you said all this in anger when you got her bill, but could you re-think the holiday? I assume form the way you phrase it you and her dad are separated? She won't see that as punishment for the phone bill. It will become, in her mind anyway, you stopping her enjoying herself at her dads. I am not judging you or telling you for one minute you *should* give that one back, but I would urge you to. Once your anger has subsided, I think you may feel bad about the amount of punishment you have given her :) If you explain why you are giving it back, she will accept everything else for what it is - paying back your �300.
I hope this has come out OK - sometimes the meaning can get lost behind the written word and I mean it in the best way possible :