I know nothing about the Orange packages, but at £12.99 seems to be slightly cheaper than other ISP's, and is perhaps a good selection, without looking into it further.
Most ISP'S use premium lines for technical support and some even use higher rate lines for basic customer care, the only exception usually is for first time customer sales, then you may find the 0800 numbers are available.
Email support is usually free, but end results can vary, depending on ISP.
ISP's charges are based on what they think the customer will pay. Some packages are solely based on the domestic market while others are based on business use, and may cost an whole lot more.
Regarding a trial, you should have looked into this before having the service. Some ISP's allow trials others do not. Those that do not, will usually tie you to a fixed contract time. Those providing a trial, usually allow customers to cancel within a set period. For instance Talk Talk allow 30 days cancellation at the moment. Other ISP's may provide a monthly contract, which will let you cancel at the end of each month if you so wish. It is best to check the terms and conditions of any package, before you agree to accept a service.
Remember, nothing is for free, especially were ISP's are concerned.