Hmm, I haven't done legal aid for about 6 or 7 years, but unless they've drastically changed the system, the idea is that if you end up better off as a result of the action, you're liable to pay.
So say you and your H have £100k equity in the house, and you sell it but you receive £70k and he receives £30k, you have made a notional profit of £20k (over your half share).
The debt may not have been taken into account, depending on circs. Did you sign something to say that the statutory charge would apply?
Not returning your calls is not on. Call again on Monday and if your lawyer won't speak to you ask to be put through to his or her managing partner.
The legal help bill which you paid may just relate to the divorce, not the ancillary relief bill.
I'm sorry, I don't want to worry you, it is possible that the LSC have made a mistake and I hope that is the case.