Chrissy, your husband is right. Take it back to the shop and have them fix it correctly. It is not causing trouble to insist that you get the service you paid for. You don't have to be unpleasant just firm and insist that the machine comes back to you in proper working order. Regarding sewing machines, I have one that is at least 30 years old and is wonderful for quilting. I had the same problem with loose bobbin thread a while back. I took it in to be serviced and the man said the timing was off and that was what was causing the problem. Did the person who serviced yours check the timing or did he just clean and oil? Take it back and have them check the timing.
I would hold off on buying a new machine unless the old one could not be fixed. Then you could see what features you really wanted and needed before making such a large purchase.