Printing before submitting deletes form

Hi guys,
I have a problem where with my enrol online form, 3 people in the last week say they have lodged it, but got no confirmation, and there is nothing on my end – email or in the listings behind the scenes. ONe lady said she printed the form first with our print button on the bottom of the page, then verified and then it disappeared. Another said they had trouble with the phone number ( I have since changed that from phone to text field as we are in Australia)
Can anyone else see any reason it would drop out for clients and that printing at crucial times would affect its lodgement?
Any advice appreciated”
http://www.benotto.com.au Enrol online. 2.7.5 is version of form builder.