I want my money back

See this Apple article: Downgrade or cancel your iCloud+ plan

Downgrade or cancel your iCloud+ plan - Apple Support (PH)

If you downgrade or cancel your iCloud+ plan, the change takes effect after your current subscription billing period ends.1

1. Partial refunds are available where required by law. If you recently changed your iCloud+ plan, contact Apple within 14 days for a refund, click -> Learn how to request a refund.

I purchased iCloud storage last Wednesday but they didn't give back any services

What do you mean by >>they didn't give back any services<< ?

If you have upgraded iCloud storage, it would take about 1 to 3 business days in order to process.

Once your request for iCloud+ has been activated, you should receive an invoice in your email box.

Check -> Go to -> Settings -> your name -> iCloud -> if you see 50 GB (or 200 GB or 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.

See -> How to use iCloud on iPhone -> How to use iCloud on iPhone – Apple Support (UK)