pls...someone help me identificate this plant

This plant was already in the house patio when I moved in here 6 month ago, climbing up this dead tree trunk. The former owner told me here in Mexico it is called Vanderbilia. In may it began to bloom and it has never since stopped to produce flower after flower. People ask me what the plant is, and I would love to have some info about it. I will appreciate any help.

 

Possibly Catharanthus roseus (Madagascar Periwinkle, a popular garden plant in tropical areas)

 

Perhaps a Mandevilla. http://landscaping.about.com/library/bl_mandevilla.htm

 

Thanks for your help.... yes it could be a mandevilla. I enclose a close up picture of the flowers and buds.. if there are some doubts. Thanks again

 

Thanks for the close-up - I'd agree with Mandevilla now