upgrade subscription not working

Hi can you sort the upgrade out asap, please 

We are sorry for the inconvenience this may have caused.

I have checked your account and you should be able to upgrade your subscription.

Guide:https://www.jotform.com/help/331-How-to-Upgrade-My-Account

May we know if an error message is shown when you try to upgrade your subscription?

Kindly try to use another web browser or incognito mode in upgrading your subscription.

Please give it a try and let us know how it goes.

Thank you.

Hi, my monthly subscription is now paying $500+ dollars you have a major bug in your system. I am still not able to upgrade... Please speak to your developers and fix this issue 

My client is extremely disappointed as would you be able to give us 3 months 3 as a goodwill due to incompetence please would be much appreciated 

On checking your billing page https://www.jotform.com/myaccount/billing the account shows your last invoice was charged $171.00 on 2018-07-30. Please provide details of an invoice sent and the amount that was charged coming from JotForm. You can post screenshots on the forum. We need this information to confirm with records on our end what charges were billed on your account.