Untill now I tried with all the methods that I know, and with none worked

//tested untill now
entity_set_model(id, "models/transform/bebivegeta/bebivegeta.mdl")
engfunc(EngFunc_SetModel, index, "models/transform/bebivegeta/bebivegeta.mdl")
set_pev(id,pev_model,"models/transform/bebivegeta/bebivegeta.mdl")
Plugin attached.
Please, if anyone has a solution post it here.
Problem solved, using the esf model changer module.