Greetings! Thanks for your query.
Treatment for acne depends on the extent and severity of the problem. Good quality pictures help us to suggest correct recommendations but it is obvious that you are suffering from severe acne from the description of your problem.
Currently you are taking Resoten (Isotretinoin) 20mg. This is one of the most effective treatments for acne. In my experience, in UK, I have not seen any person who did not respond to this treatment. But you need to take the right dose and continue for at least 4-6 months. We tend to start at 20mg for a month then increase the dose to 30-40mg/daily depending on tolerance. Dose can be increased to 1mg/kg/ day.
You are also using Cligel (Clindamycin). In my opinion combination of topical retinoid and antibiotic (like Clindamycin/ Benzoyl peroxide) is superior compared to antibiotic application alone.
The other medication Aziderm 20 does help to improve hyper pigmentation. There are other options also available if you don't see much improvement but the acne has to be controlled first.
I can assure you that acne problem, how severe it may be, does respond to the right medication taken for the right duration. But compliance with the treatment and having patience and positive attitude is essential.