This includes injection damp-proof courses, tanking solutions and various other proprietary systems.

The theory of a lot of these systems does seem appealing: they are usually quick and they come with a guarantee. The problem is that while a lot can be made to work in a laboratory, in practice they do not work. Worse still, the guarantees they offer are always so heavily caveated that you wouldn’t be able to raise a claim if you could prove the treatment had failed. To prove in court that it had failed you would need solid data quantifying the before and after - and not just the obvious fact that there is still an issue!
This is actually very difficult to do, as quantifying moisture content in a structure takes a long time: and requires either invasive testing with samples being sent to a laboratory, or a very expensive piece of equipment and thorough repetition against known datums.
If you own a Listed Building, your Conservation Officer will never agree to any of these treatments, and if you carry one out then you will be breaking the law.

In order to treat something, you must first understand what’s happening - the defect diagnosis needs to be done by a suitably trained professional with no bias or links to any company or particular treatment.
The good news is that in most cases it is usually simple to treat - and with the right thinking, process, and documentation behind it the Consent will not be refused.