scale infestation

[Smitha]

I have 2 phals which have scale infestation..I tried rubbing their leaves with isopropyl alcohol.It reduces once applied but eventually comes back..One of the plants were super healthy with regular blooming cycles.But now it's reduced to just one shrieveled leaf with the small hard shells on..What should i do with these 2 plants??..Will they come back or should I toss it??