If you are planning to keep that radio for the forseeable future, it may be a good idea to buy a serviceable spare. I have bought satisfactory avionics equipment on eBay. Just make sure that the seller guarantees the unit to work as expected.
Or just bite the bullet and go for something else. But I have to say its the first problem I have ever had with the unit since I have owned a C150 and the shop is "overhauling" the radio FWIW.