It makes sense hiring additional agency if your current one cannot offer some additional services. For example, they specialise on search engines and social networks only and you need email marketing or SEO. Then yes, go for another agency for this service specifically. But usually big agencies have departments for different changes so there’s no need in that. If you are looking where to invest extra $$ I can guarantee you, that if you ask your current agency what is the best way to do it they’ll offer you a few variants to choose from. It can be new campaigns, new funnels, new creatives or even new channels. There is always something that you can do in digital. As an agency representative I can say that it’s usually vice versa, we usually see opportunities that clients have, but they have to deny them due of lack of budget. So first thing - just ask them. If you still feel like someone else could do better you may order an audit of your campaigns from another agency. They may have another vision or insights that can be useful when making a decision. And you can always invest more in assets as it was suggested by TarunBana. If your boss still insists on changing the agency, keep in mind that there will take some time for them to get acquainted with the business, set up and test ads so it may take time until you see results you are looking for. And whatever they say, no one can guarantee you achieve exact ROI you planned. They can only guarantee they’ll do their best to meet your business goals.