real loud clunk passenger side on 2007 Chevrolet Impala

i have 07 impala ss chevy replaced trans in it and ever since when driving for about 30 min it starts to clunk real bad brought it back 3 times and they never find any thing wrong i told them it is the axels and they say nothigs wrong how can i get them to fix it

Asked by for the 2007 Chevrolet Impala
Go back to them one more time go for a drive with them and go for a drive with a mechanic and point out and identify the exact noise you are concerned about.