bestsoftsolutions.com froze computer so I could not do anything but click on their pop up, Internet

My husband was working on our family computer and it froze up. He could not click on anything, could not close down the screen. It would not let him do anything. He ASSUMED that our software must be expiring so he click on the bestsoftsolution & purchased their product. He said this had been popping up (on his screen only!) for some time so he completed the transaction. Since I take care of EVERYTHING that goes right or wrong with the computers he should have checked with me. I had AVG software on the computer and have used them for many years to keep the computer clean of problems. But the web sites my husband visits invite this type of problem. I would like the $99.90 back.!!