ieatdonnaskebab

Hi can anyone help I have a 1990 V8 auto and I have just had the gearbox fluid changed, the old fluid was extremely dirty. The problem is that now when I pull up to a standstill and go to pull off again the box doesn't engage a gear and will rev and then drop into gear with a bang and seems to be ok then until I stop again, it will not engage any gears including putting into reverse. Any help and advice would be appreciated. Regards Anthony