Cold telephone call

Couple of days ago had a telephone call from a guy who said he wanted to buy my FIT agreement  for our solar panels.  He said he would pay a substantial lump sum, we would still own the roof and the panels but they would take the payment, contract would be changed to their name.  Told him not interested.  Talking to BIL later he had the same call and out of interest ask them for a price, it was derisory, about a third of what he would earn (tax free)  in the next 20 years!  Anyone else had calls like this?