VW Cabrio alarm problem & key won't lock door

2002 VW Cabrio alarm problem: alarm will not un-set. Door will not lock using the key OR the remote. Hitting "alarm off" button on remote, it unsets, then arms again immediately. With engine running, alarm will set itself to on (beeping to let you know it's armed), then start sounding if you don't hit the "alarm off" button within one minute. Brand new batteries in remote, both remotes having same problem so it's a problem with the alarm itself, NOT the remotes. Remote door lock and unlock stopped working 5 years ago. Any suggestions?