How to change Subscription from Monthly to Annual service plan

Also, is there any way to make an annual payment, rather than monthly payments, and if so, is there a discount for prepaying for a year's service?

Yes, this is possible.

We can change your subscription in our system to make annual payments instead of monthly payments. Once we do this change there will be a charge made to your credit card for the new subscription (with a discount for the value of the days remaining in your current period).

The yearly subscription for the Premium plan which is the one you have is $90, you can also purchase a bi-yearly plan which costs $139.

So, if you're ok with us making this change let us know so we can proceed accordingly.