iPhone 12 Max Pro charging problems

I’m having problems getting my new iPhone 12 Pro Max to charge either plugged into the usb from my iMac like I’ve always charged overnight or the belkin wireless charging pad I got from John Lewis, well it does charge on there sometimes as long as you’ve got it in the absolute perfect position and even then it’s hot and miss???

Have I got to bite the bullet and buy the new mains plug from Apple for £19?

Any help or advice would be much appreciated 👍🏻👍🏻😂