Vacuum does not work

I bought a BISSEL EASY VAC about a year ago at Pick n Pay Hyper Montana. I had a problem after 3 weeks with the machine... it overheated and switched off after 15 minutes of vacuming. Tevo came to fetch it and apparently replaced the motor. I do not use the machine because I have a domestic worker. I used it now for the first time again and after 5 minutes of vacuming, it switches off........ I really am not impressed with the machine at all.