Uhmmm most likely gone to a apprentice admin worker they are taking on loads of kids for office work across the UK with no experience just that they are cheap labour so I reckon a lot of these issues are because of that Not saying kids are thick
I have been to an Iva company on another business trip and from what I saw was a huge office with loads of desks and teens all answering phones etc
Redundancy you will be told to hand it over I would suggest that you say ok you have a chunk of cash you want to pay a fair settlement and see what they say You are not far off the total amount owed so an agreement could be brokered I would come up with some figures say what you would have paid in as normal and then double it if you can
Only your IP can tell you and as Melanie says if you dont hear nowt just pop it in your bank and ask them to make a seperate account to hold the money with its own account numbers
Send your IVA company a Letter emails are pointless as they are easily deleted or not received so you would get fobbed off
Letters sent recorded you are playing it straight and covering your back Then leave it at that If you dont hear anything leave your cash in the bank and make interest for you at least you will know your IVA payments are covered Also you may get your job back or not redundant Dont cross bridges til you get to them just look after yourself ok and remember its your IVA and how you do it is down to you they only control the admin and finance
good luck