I’m a dental therapist, but spend most of my time doing hygiene work. It’s so sad you’ve had such bad experiences in the past, it never needs to be that painful.
Couple of things to consider here. A “deep clean” is layman’s terms for subgingival instrumentation, essentially cleaning into gum pockets. When people have gum disease the attachment of the gum to the tooth is lost and a pocket forms, forming a gap between the gum and the tooth. To treat this, the root surface below the gum line needs to be cleaned, in most circumstances done over a couple of sessions using local anaesthetic.
If you’re telling the hygienist you need a deep clean when that’s not what you actually need, it’s possible they’re looking in your mouth and seeing you don’t have any gum pocketing, so try to convince you you don’t need the anaesthetic. It would be more helpful to tell them you have dentine hypersensitivity and request local.
I caveat this by saying I always listen to my patients and if they tell me they find cleaning really painful and want local then I’ll give it to them no problem. But in many cases the injection is more painful than the actual treatment, so I’ll give patients the option of trying with some desensitising paste first (not numbing gel as this only numbs the gums and won’t help sensitivity) and in most cases when patients are willing to try it works really well and is quicker, less painful and you’re not left with a numb mouth for hours afterwards.
I’m really lucky in my clinic in that I’m given plenty of time, however sadly lots of hygienists work under massive time pressure with not enough time to complete everything they need to do, and adding the extra time that’s needed to do the local adds stress. Not your fault I know, but not the hygienist’s either as appointment times are dictated by management. It may be helpful to explain you need extra time when booking the appointment, of course you may need to pay extra for this.
Finally, and I mean this kindness and it may not be the way you act in real life, but your post makes you sound quite aggressive. Maybe have a think about the way you speak to the dental staff, they’re more likely to help you if you speak to them with kindness.