Is $2,700 to run underground power and trench 250 feet a fair price?

I am frustrated that the contractor did not properly fill and compact the 250-foot trench after running the underground power. The trench was left as a ditch, making it impossible to mow. The contractor only kicked some dirt over it, which compacted after rain. I have arthritis and cannot physically fill the trench myself. I am concerned about the depth of the bare UF wire (8-10 inches), questioning if it meets code (national code mentioned as 24 inches without conduit, though 8 inches might be okay with GFCI). I haven't paid the contractor yet and am considering not paying or having someone else fix it. I feel the price ($2700) was high for the work performed and the quality. This experience makes me realize I need to be much more specific in contracts and knowledgeable about construction details for future projects, like building a house.