If it's only the front panel audio, then it's not too bad. If you also damaged the case speaker, it's not too bad either. you can probably buy a little speaker thing, one came with my case iirc.
Talk to OcUK about this. I hope it didn't fry anything else, but you may be able to RMA the case and maybe the motherboard if it is damaged, or OcUK maybe able to provide you with parts to replace, but I would suspect it's RMA time. Could be that the speaker was defective and shorted the cables. Talk to them anyway.