The sellers with the 99p listings have been doing it for years and still continue to do it so obviously the "actions" you are taking are not severe enough.

Each one of these listings has numerous policy breaches so even if you gave them the benefit of doubt on one theres ten other breaches

No item listed for sale

Search and browse manipulation

Avoiding ebay fees

Keyword Spamming 

etc

etc

Us honest car parts sellers run the gauntlet of returns,bad feedback,late deliveries and god knows what else and pay you fees on each sale

These listings avoid all this

Instead of roadshows and telling us how to sell why not devote a dedicated team to sort car parts out once and for all!!!

I could sort it out in a month its easy,get rid of those cheating fees and the genuine sellers then sell more generating far more revenue for you its a win win for everyone including the buyers too as they deal with genuine sellers and the transactions are done through ebay.