If your spouse is refusing to comply with your separation agreement the first step would be to try to talk to them about it and gently remind them that they agreed to the terms of the agreement and that you intend to enforce your rights under that agreement.
The next step is to see a family lawyer and have that lawyer write a “demand letter” to your spouse informing them that they must comply with your request or risk court action. Sometimes you may decide that it is worth the cost to have your family lawyer write two or even three letters to your spouse depending on the circumstances.
Finally, if your spouse will absolutely not comply with your requests, then you must file your agreement with the court and begin a court action to enforce your agreement. This would be costly and take some time so it would be a good choice only as a last resort.