I doubt that anywhere will give a free estimate. It can take ages to diagnose the fault.
You might be able to say to them "I have an xyz model TV & such & such is happening, do you know what this fault may be & how to repair it, what might that cost?"
If you could post the exact model number & can look on the TV sites I know to see if there is a common fault.
Now last Friday I would have said.
It's your colour TV license, it's the new automatic reminder that it's about to expire. It goes intermittently B&W until the day it does expire & then stays that way until you replace it.