TL; DR: I went for 1-2 months without buying anything other than the supermarket shop at a discount supermarket. It kicked my shopaholic habit. Try it.
Long response: I always used to buy hair products, clothes and make up, but I stopped and told myself I would use what I have (e.g. if there was a new condition I 'had to try'). This helped kick my habit, I realised I didn't actually need or even enjoy all that stuff. It wasn't making me happy, it was just an addiction or craving I needed to scratch. Like other cravings, after you avoid them they diminish to nothing.
Do this for 2 months: No beauty treatments, hairdresser, clothes, beauty products, take aways, coffees, 'days out' etc etc etc. It doesn't actually make life more fun. Make your own sandwiches and coffee at home and go for a walk. Use up the shampoo and conditioner: cut the packet open to get out the last parts. Cancel Netflix, Disney Plus etc. Wear the clothes you have already. Pluck your own eyebrows and paint your natural nails (with the old nail varnish in the back of the draw). Keep your phone and go PAYG once the contract expires. Get rid of the HP car and buy an old banger. Share that old banger with your partner. See if you can work from home to cut down on commute costs. Walk, don't drive. Cut down on meat. If you want a take away, drive to the discount supermarket and buy one of their freezer meals - do this once per week maximum. Batch cook. Buy mince meat instead of full cuts. Chicken thigh fillets instead of chicken breast fillets. Buy spices and cook from scratch. Find cheap recipes - cottage pie, chilli con carne, curry. Stretch and bulk out meals with potatos, pulses, lentils (people make out as if it is awful, but it really isn't). Ditch ready meals. Put on an extra layer or two or three before putting on the heating. Dry clothes outside. Wash up in the sink instead of the dishwasher. Fire the cleaner and clean the house yourself. Stop taking the car to the car wash: wash it yourself or let it stay dirty.
OK I got carried away and some of those aren't '2-month' things. But hopefully you get the drift.
You'll get into a 'no spend' habit and wonder how you used to waste £100s per month on this shit. When you see other people telling you what they spend their money on you will feel shocked.
A friend was horrified when I suggested they make their child a cheap chilli con carne when they were short of cash "I would never do that to them". WFT I eat chilli all the time, it isn't "doing" anything to anyone.