Acuity Add on feature - Multiplying customer booking price - UREGNT HELP!

Urgent Help! No support until Monday, which is absolutely ridiculous.  

Can anyone help solve my issue with Acuity?

On my class booking option, the add on's (which are body scrubs and face masks) price are being multiplied if a customer is booking more than 1 person onto the class. 

Eg: 2 people on class = £30 + 2 add on's each (should be £20 - £5 each) but is totally £70. So the system is multiplying each add on line by 2, as the customer is adding 2 people to the class. 

As instructed by Acuity, I have created a separate SKU for each treatment eg: Face mask for 1 £5 / Face mask for 2 = £10 and so on. But clearly this doesn't work if the customer is trying to book multiple spaces for themselves and friends to a class. 

Does anyone know how to remedy this?

Absolutely desperate as I've had to take off my treatments, so customers have no way of paying for extras now. This is lots of money lost for awful set up. 

Thanks 

Lorna