Propriatory connectors, I would stick with a Volvo unit. You can fit the one with the CD changer, it should be a streight swap and all the wiring should be in place. Try eBay for a radio.

But you can change the connector or get an adapter, they are available. It is just messey, the cable is short.

Is it also jumping stations on the radio? Sounds like the control panel got damaged, perhaps someone sprayed cleaning fluid directly onto the radio instead of onto a cloth. It is fixable, only has to be stripped and cleaned out.