Hiding your fiberglass bathtub behind the shower curtain is one way to deal with scuff marks, but it's not a solution. In most cases, scuffs only affect the surface; they're not permanently damaging. Instead of hiring a contractor, remove the scuff marks yourself with products you likely already have on hand.
Things You'll Need
Water displacement lubricant
Mild abrasive cleanser
Spray water displacement lubricant directly on the scuff marks. Allow the spray to sit for a minute or two.
Rub sprayed areas of the fiberglass with a soft cloth. If the scuff marks persist, spray with water displacement lubricant again until the marks come off.
Rinse the fiberglass tub surface. Sprinkle the tub with a mild abrasive cleanser. Scrub with a soft sponge to remove residue and rinse well.
Because water displacement lubricant emits fumes, ventilate the bathroom before you start. Water displacement lubricant makes the tub slippery, so don't skip scrubbing the tub afterward.