Received a call from sky offering a discount on mobile how can I find out if it was a scam

[CarolCa]

Received a call from sky offering a discount on mobile phone sounded ok but am not sure if it was a scam or not. How can I find out 

[PandJ2020]

It almost certainly was a scam.

Did you give them any details, such as your password?

[twilight+princess]

It's a regular scam. Caller states they can save you 30%-40% on your bill & may offer to send you a gift, at some point they'll ask for log in details to your account so they can process the saving but instead they'll order expensive devices. Once sent you'd receive another call saying the wrong gift was sent & to return the devices. Should a customer do this then they'll be liable for the cost.