HOW EASY IS IT TO FIX WINDSCREEN WIPER PROBLEM ON MY 03 RENAULT SCENIC?

RECENTLY MY WIPERS WILL NOT SWITCH OFF. THE INTERMITTENT MODE DOES NOT WORK AT ALL, ONLY STANDARD AND FAST. I HAVE HAD TO REMOVE FUSE AND REPLACE WHEN IT RAINS. GARAGE NOW SAY TO RESOLVE PROBLEM WILL HAVE TO REPLACE CENTRAL COMPUTER (COST OF PART £400 + LABOUR + VAT). IS THERE ANOTHER WAY AS NO OTHER ELECTRICS ARE AFFECTED?