Creeping Plumbago, Plumbago ceratostigma, is not considered invasive, as in escaping into the wild and displacing native plants. Rather, I would characterize it as an assertive opportunist, finding its way to a few sunny spots in a mature mixed border. If the garden you mentioned is new, that would account for Creeping Plumbago coming on a bit too strong for your liking. But in time it will be shaded out by other perennials and shrubs. In the meantime think of it as a handy mulch, keeping the roots of your other plants cooler in the summer.
As for ivy removal, visit this link to the same question from our answer archives: Clearing land of Ivy. Use our Search feature in the Experts section to access all previously answered questions. I hope this helps.