Corrosion and bad paint

Moin I want to protect my car from rust. It starts all over flight rust. So far I have used sonax flight rust remover but everything does not go away. Manufacturer ? – Type ? Mercedes 250 td Kombi bj 1992 – Color 147 White – Metallic (j/n) ? No – Age ? 26 – Care history in a few words, like e.g. „So far approx. every 3 weeks washing system, 1x a year hand polish and waxing , 1 times a week with high pressure cleaner 1 times a year by hand with red white polishing paste – Description Condition, like e.g. „ e Washer stripe, on the front insects burned, approx.3cm long scratches in bonnet, wheel runs made of plastic bitten off everywhere flight rust Partially repainted Rather little shine – if necessary targeted photo(s) of defect(s) to be removed – previously used polish/paint cleaner ? – previously used wax/sealing ? – Budget: What do you want to invest maximum for the upcoming action on care expenditure (abs. pain limit) ? 250 Euro – Conditioner: Comes a professional – Is the purchase of a polishing machine (power socket!) with corresponding professional means in question (several hundred EUR, but if necessary lasts several years) ? I don’t want to invest more than 250 Euro – Do you regularly drive through a washing machine and have that further, or does it come into question ? No It would be in question – How much time is provided per week (approximately) for car care ? One hour – How often per year b is you ready to polish / grow ? 3-4 times it would be nice if the seal protects the paint permanently.