Marketing and Advertising gets you in the door with potential new client decision-makers…
But, once there, you are in "sales-&-selling" territory. That territory is unique on its own and demands skills that marketing and advertising do not hold, contain, nor teach.
B2B situations almost always require in-the-face meeting with the check-signer present. Knowing that you have to adopt a sales technique you have to learn.
Remember: the decision to buy your services (or not) is made when you are NOT in the room. The decision is usually made by the check-signer and not by requisitioners. Check-signers almost always base their decision on business concerns, not on technical concerns.