Sounds a little like an excuse to me. The ACS state or used to state on their website that they'll accept references directly from employers, does this get round the Data Protection restrictions? Try suggesting it to them and see what their response is.
The basic reference that they're offering will negate the need for payslips etc as they only prove you actually worked for them, not your duties. Do you need the experience from these companies to count towards your overall experience years, i.e. can you live without the ACS and DIMA counting this experience, but still be left with enough to satisfy the requirements of the two bodies.
Try emailing the ACS directly and explaining your situation, I'm sure this is a common problem. You could maybe take a chance and draw up a stat dec explaining the situation and sending this in with you RPL application. If the ACS aren't happy with that they'll request more info and allow you some more time, might be worth a punt.
If you don't get anywhere with the above options, you may need to engage an agent with specific experience dealing with the ACS, for complex situations agents are invaluable. I can recommend one if need be...
Hope this helps, PM me if you like.
Help With BOND Sender: popeye
Hiya angel only just seen this post, but seen you have sorted it now. would just to add its not a hard process to...