Changing tariff as an existing customer

Hi.

i thought this would be simple, but it’s proving difficult. I’m an existing OVO customer on a rolling Simpler Energy tariff and thought I’d like to try and move to a fixed tariff before the increase.

Tried logging into account, lots of options around boiler cover, new boilers etc; nothing on new energy tariffs. 
 

Very easy as new customer, why so difficult for existing customers? If I try and choose the plan as a new customer it tells me I’m an existing customer and should log on to my account!!

how do I get a new tariff!

update: finally pushed the right buttons and got it working, but not very intuitive 

thanks,

colin