Ape Factory

Couple of thoughts. First, the stock transmission cooler sucks. RMR makes an aftermarket unit which is exceptional and has been on the market for years. There's finally a kit for the S4 and S5 after it being exclusive to the RS5 for a few years (same transmission).
https://redmistracing.com/ols/produc...c-transmission

Second, I would check to make sure the fluid level on the ATF side (clutch DSG fluid) is at the proper level. Seems incredulous but most dealerships don't know how to properly service or fill the ATF side (to fill, car running, temp at 30C to start, finish by 60C in a nutshell). I would purchase a Ross-Tech VCDS if you don't have one already and run the various transmission and clutch adaptations.

Third, if you do not have a Ross Tech VCDS, get one. Run the various transmission and clutch adaptations. A lot of dealerships don't do this after a full transmission service (ATF or ATF/MTF side service).

If they replaced the mech four months ago, assuming they didn't use new old stock, you have the latest/greatest mech with the improved PCB board and larger heat sink. But again, the OE transmission cooler is an afterthought at best. It literally uses hot coolant to "cool" the ATF side of the transmission. And despite the upgrades, even the latest DL-501's are prone to issues.

So check fluid levels, run adaptations and do some preventative maintenance mods like the RMR cooler. Cheap insurance vs. the cost of replacing the mech and it's a bolt-on kit, no cutting.