Wordpress Ez Form Calculator Fix

I need someone very experienced with electronic forms to help me with a couple of conditional formula problems I am experiencing. You can see the form maker I am using here. [login to view URL] And you can view my form here. [login to view URL]~fieldvcampsite/cost-calculator/ I need these variables fixing, Camping/Tent Per night. £12 Number of People 2 (+£0) 4 (+£2) 6 (+£4) +£5 Per Night Electrical Hook up Per night +£5 Per Stay Gazebo Touring Per Night Motor Home/Camper Van/Caravan £15 Adults 2, 4, 6, Children 1, 2, 3, 4 No extra charge +£5 Per Night Electrical Hook up Per night +£2 Per Night Hardstanding +£5 Per Stay Awning. +£5 Per Stay Porch Awning +£5 Per Stay Gazebo Trailer Tent £12 Per Night No. of people 2 (+£0) 4 (+£2) 6 (+£4) +£5 Per Night Electrical Hook up Per night +£5 Per Stay Awning. +£5 Per Stay Porch Awning +£5 Per Stay Gazebo When items are not applicable to a form of holiday Ie Porch Awnings are not available for Camping/Tent I do not want it visible. The total cost must be calculated using the form (this is already functional). But I also need a 20% off if they input a 6 digit number,