We have had major issues with our pool finish. Finest Finish Sparkle Quartz. The pool is less than two years old. Can’t keep the ph/alkaline in check. The finish is deteriorating. Our PB is willing to take out the plaster and redo it. We are going to upgrade to Finest Finish Radient Finish. Our pool is about 14,000 gallons plus spa. The PB is covering the costs except the upgrade. They want to charge us $5,600 for this upgrade. Is this high or average? Thanks for any help with this.