Negligence almost caused an accident on N1

Had four tyres fitted today 6th of November 2015 at a workshop owner by tyres and more and later on the day when driving to Limpopo I heard a strange noise as if we drove over something, but there was nothing when we stopped to inspect our car, one of the tyres the knots were loose , we called the workshop and Deon said there is nothing he could do as he check the car before it could be handed over to me, then told my husband to jerk the car and fix it himself as he cannot come out for one tyre, we had just spent 11600 on that day to fit the new tyres and this is the attitude we get and the fact that we could have killed he did not seem to care, to our luck AA came out and assisted and confirmed that the right rear tyres was not properly fitted, Khanyisile Mthombeni