DVSA letter re MOT extensions

Just had a customer on the phone saying he's had a letter from DVSA  advising him to get his car tested by the end of the month or he won't be able to tax it or it may be impounded, I checked on the mot history page and it has had the extension added and is showing as tested until the end of November, has anyone else heard of this happening? or is some of his mates winding him up? He's booked in for tomorrow afternoon so I'll get a look at the letter then and maybe try and get a copy of it to add to this post.