Looks like you already got some good advice about going else where and then suing. I would add that it may be a bit better if you tell Cottman what you plan to do; they may make a better effort to fix it correctly.
Not too much of a WAG: They just slapped a rebuild kit in the trans, did not check any of the specs like end play on the assemblies, just reused the same selective washers. May have made a mistake with the valve body, pump, and may have cut a seal during reassembly and did not find it or dig that deep on the subsequent repairs to find the bad seal if one or more had been damaged.
Those problems can also cause the friction plates and or band/s to ware at an extreme rate or burn up.
HTH or gives you some arguing points with Cottman.
BTW, I got a check from Cottman because of some class action I became a part of about seven years ago - but it sounds like you have been made aware of Cottman’s reputation. Good Luck.