Purple shampoo help please

[El48]

I just had my hair colored a dark purple with subtle blonde highlights and my hairdresser told me to use a purple shampoo. What are some recommendations for the best purple shampoo(s) that I should use and how often. Thanks for any help. 

[GG84]

@El48 

I actually wouldn’t do this. The way you are describing your hair to me sounds like a plum colour with thinly weaved blonde. 
Give it a few washes with a good quality colour protecting shampoo and conditioner like 

Kérastase Chroma Absolu Shampoo for Fine to Medium Color-Treated Hair 8.5 oz/ 250 mL 

Kérastase Chroma Absolu Strengthening Conditioner for Color-Treated Hair 6.8 oz/ 200 mL  to see if any violet bleeds into the blonde first. Your blonde will either end up stained or toned. 

[El48]

Thank you for your help and product recommendations.