i would suggest, don't pay anything else untill the job is finnished to her satisfaction.call or visit the shop supplying the goods and explain that they have a duty to use skilled fitters and to do the job properly. try to haggle a discount for needing a third day off to allow them to fit the rest and make sure it's at a time that suits her, not ' when we can fit you in'
also if she goes to the shop tell her to make sure if possible other customers know she has a complaint by talking loudly 'cos the shop won't like the bad publicity!
and lastly, try to make sure the fitter is always in view 'cos you never know when they may have a ' little look about '