As a former garage door technician, I can confirm the comments above. A spring upgrade would have been plausible however several factors to bear in mind when it comes to springs 7 foot doors require 7 full spring rotations and an extra 1/4 turn for good measure in order for the door to raise all the way. 8 foot door, 8 rotations (so on and so forth) your garage door opener has force limit settings on it, most modern ones are automatic, and older models will have two turn dials that symbolize opening force and closing force, if it’s turn dials, check to see their current positioning (max or min) if both dials are set to max this will indefinitely shorten the life span of the motor as it’s basically being told that it can open/close as hard as it wants without repercussions. Not only is this bad for your motor but it also means if the spring breaks and or your door closes while someone is in the way (providing it doesn’t trigger the safety sensors that should be installed on the vertical tracks of the door) the opener won’t stop, it’ll keep closing crushing anything in its path. Resulting in harm to a person or objects beneath it. Likewise if your spring is broken and the door weighs far more than the opener is intended to pull, it’ll keep trying to open the door inevitably burning the motor out itself. Spring upgrades are not only costly but going back to my statement at the top, higher spring ft/lb torque ratings mean that if the door is too light with the upgraded springs at 7, 8, etc rotations. Those springs are useless. Overwinding the springs can also shorten the lifetime of the springs themselves. I would have the garage door company come back, take the insulation off and revert the spring tension to how it should be. Otherwise the costs long term would cost you the same as an R35 properly insulated garage door + new hardware.