When they planted my arborvitae they did not cut open or remove the twine or burlap from the ball, will this slow their growth???
Hennepin County Minnesota tree planting
Although some people thought that the twine and burlap would decompose and cause no problems so they left them, it has been shown that they cause problems. Wire ties are especially problematic, as is leaving the burlap over the top of the shrub. See https://s3.wp.wsu.edu/uploads/sites/403/2015/03/bb-root-balls.pdf This is a little older paper, but also says to remove most of the burlap: https://www.extension.umn.edu/garden/yard-garden/trees-shrubs/planting-and-transplanting-trees-and-s... You may want to have the company come back and remove the burlap and check that it is planted at the correct depth.