Hi,
I have been in exactly the same circumstances.
I was under the (mistaken) impression that once the overdraft was being paid off via the IVA they'd leave my wife alone.
Bear with me, I might ramble a bit here...
An overdraft on a joint account is the responsibility of both account holders. They are both liable for all of it.
She owes the whole amount and so do you (not half each).
The bank is doing what it can to get the money back.
However, there is only one debt. Therefore, whoever makes a payment, the one debt reduces. So as your IVA company make dividend payments, the debt will reduce.
Now - a very important point. You should never use any of your own personal surplus income to pay anything off the debt, even on your wife's behalf. To do so is "creditor favouritism" and unfair to other creditors. You are paying through the IVA fairly and that's that.
In my opinion, your wife needs to make an offer to pay it back monthly and ask for them to freeze the interest (which is a pretty standard request).
My advice is for her to answer them promptly, in writing only (not email/phone) and keep all correspondence. Make an offer to pay and explain that it's as much as you can comfortably afford each month. Ask for them to freeze the interest, which is a very normal thing to ask for.
My wife has been paying £8 a month for 2.5 years now with no issue.
Alternatively, if you are in a position to do so, your wife can pay off the debt completely. She will then actually take the creditors place in the IVA, receive dividend payments and get to vote! I don't know much about how this works but it does happen - experts on here like Michael Peoples I believe know more about this.
Above all, do not panic, worry or fret. But know that you cannot take this away from your wife and she must deal with it. However, you will only likely be able to pay a small amount. They will know about the IVA and accept it I'm sure.
We worded the letter something like "...as you will appreciate, all household income is spoken for in an IVA leaving very little surplus. The most I can offer to pay at this time is £8 per month. My husband's IVA is subject to annual reviews and I will contact you if my circumstances change."
Hope this helps, keep us posted!
One pay-cheque away from oblivion!