I Was Prescribed Primolut-n To Delay My Period But The

I was prescribed Primolut-n to delay my period but the instructions given were to take 1 tablet twice a day once my period had commenced. I started menstruating Tuesday morning so I have taken 1 tablet twice a day Tues & Wed. Today is Thursday & I'm still menstruating. It is possible to cease this now it has already commenced? Can I increase the dose? Many thanks