If the IVA was extended because of equity then it should clsoe after 6 years anyway. If it was originally 6 years it could be extended by a year and you could make an offer to avoid this.
the iva has been extended for 6 years which is now at the end and they have asked us about releasing equity but our provider have said no they say we still owe 12,000 would it be possible to make them an offer of 6,000
That seems very reasonable but would depend on your monthly payment. If there is equity and you cannot get it out your IVA will be extended another year. If you can raise perhaps 10 months contributions that should be enough for creditors and the full twelve would close it down.