Sad to hear about the your problems with the UTV.
I assume the installer can perform some testing to confirm that your "complex/messy wiring", possibly your Sat. LNB, or your existing setup in general isn't to blame for the "dead" UTV tuners...
Some checking of the History Log might give you some clues if the UTV was showing early signs of death or there was something wrong with the setup before. A direct run to the Sat's LNB and UTV might eliminate possible issues between Point A and B. Also remember to check only one tuner/cable at a time.
Not sure how your existing setup is configured but it might be possible the UTV has "defaulted" to the wrong Sat setup... which might be hiding certain Sats/LNB feeds.
PS Just in case you still wanted to supplement the "upgrade" with a UTV (if it's functional).