an existing customer with 100, 150 or 215 plan subscribes during in mid-month, will the customer get the service immediately ?

No, The customer has to wait for next auto-renewal, not Renew Now, to get the free service. There will be coming enhancement which will allow the customer to enjoy the service immediately.

Content Providers
What is OSN+?
Is OSN+ add-on available for all packages?
What is the free trial period for OSN add-on?
Can customers take the OSN in Virgin Mobile website?
I subscribed through traditional channels (USSD, dealer App), do I still get to have OSN add-on?
Can Member Care team add OSN to customers from the Support Tool?
Is the OSN+ offer available for new customers only?
I took one of the three VIRGIN bundles (100,150, 215) and I changed to another bundle (e.g. VIRGIN 70), do I get the OSN+ add-on?
Can Member Care team add OSN+ to customers from the Support Tool?
The customer is already in one of the eligible plans for OSN+(100, 150, 215), and he already subscribed to Anghami or STARZPLAY Offer, can the customer change to OSN?
The customer already has a OSN account, will he receives a SMS with a new username and password?
The customer already has a STARZPLAY account, will he receives a SMS with a new username and password?
The customer is already in one of the eligible plans for starzplay (100, 150, 215), and he already subscribed to Anghami Offer, can the customer change to STARZPLAY?
Can Member Care team add STARZPLAY to customers from the Support Tool?
I took one of the three VIRGIN bundles (100,150, 215) and I changed to another bundle (e.g. VIRGIN 70), do I get the STARZPLAY add-on?
Is the STARZPLAY offer available for new customers only?
I subscribed through traditional channels (USSD, dealer App), do I still get to have STARZPLAY add-on?
Can customers take the STARZPLAY in Virgin Mobile website?
What is the free trial period for STARZPLAY add-on?
Is STARZPLAY add-on available for all packages?
How do I activate OSN ?
What is STARZPLAY?
Can Member Care team add Anghami Plus to customers from the Support Tool?
I took one of the three Virgin bundles (100,150, 215) and I changed to another bundle (e.g. Virgin 70), do I get the Anghami Plus add-on?
Is the Anghami offer available for new customers only?
I subscribed through traditional channels (USSD, dealer App), do I still get to have Anghami add-on?
Can customers take the Anghami Plus in Virgin Mobile website?
What is the free trial period for Anghami add-on?
Is Anghami add-on available for all packages?
How do I activate Anghami Plus?
What is Anghami Plus?