If you are on a good DMP then the company who you have this with should do what they are being paid for and deal with it for you.

Have you made them aware of this?

If you take out further credit you will break the terms and conditions of the DMP and also getting further credit out is never the answer.

Default notices are nothing to worry about if you are on a DMP because you will more than likely get them for every debt you have. Your DMP company should give you this advice.