Don’t ignore your gutters
Two notes #1 20 feet is going to cost you more per foot that 100 feet. #2 All prices are relative to Your market ie Omaha is less expensive than St Lious. Here expect to pay on the 100 foot job $5 to $6 per foot of gutter (5" aluminum) plus the $4 to $5 a foot for the downspouts and $15 to $20 for soffit and facsia covering ie vinyl soffit panels and painted or vinyl clad aluminum covering the fascia. In the trade a soffit & fascia job.
Jim Casper Gutter & Gutter Cover contractor in Iowa & Nebraska
ps see my website for blogs on gutters & covers
Old Waterproofing Contractor & Gutter Contractor
Not knowing what type of eaves (the lower edge of the roof) you had before the new soffits were intalled I have to guess what might have happened. If you had closed eves (no soffits, just rafter tails with blocking between) before as was done on some older homes it is possible they removed or drilled holes through to the attic. When this was done there should have been a baffle installed to direct the air flow up and over the insulation. This would only be possible for the soffit installer to do if the wood blocking was removed and not just had holes drilled in it. If the insulation contractor did not go all the way to the exterior wall that could very well be the cause or it he did not make sure the insulation was pushed down to make contact with the ceiling material. If the house was never cold before I would bet the problem is at the eaves. You should call the insulation company for an answer.