I’ve been paying £.079 for a year now for 50GB, but I still keep getting messages stating I’m running out of storage?? I’ve not gone above 15Gb, so why did I pay for 50GB cloud storage without getting what I payed for??

If you are talking about iCloud storage, check -> Go to -> Settings -> your name -> iCloud -> if you see 50 GB (or 200 GB ot 2 TB) then you have an iCloud subscription.

If you have an iCloud subscription, you will receive a monthly bill from Apple, check your email box.

You pay monthly for iCloud storage.

See the following Apple articles:

Check your iCloud storage online or on any device

Check your iCloud storage online or on any device – Apple Support (UK)

Manage your iCloud storage

Manage your iCloud storage - Apple Support

Change your iCloud settings

Change your iCloud settings - Apple Support

If you are talking about Gmail, Google drive storage reach out to -> https://one.google.com/about/support?hl=en