One of the irritations of using SP's credit points is that they eventually go dormant - they don't actually vanish from your account, but can only be activated if you buy more.

SP has now announced that between 5-22 May (2016), inactive credits can be activated without purchasing more. To do this, log in, go to your shopping basket and enter the code spring2016 into the voucher code box and click "use voucher". The expiry time will reset to 365 days, and you'll get an email confirming this (it'll say that 0 credits have been added since you're only reactivating old credits).

I wonder whether their system's getting clogged....