You might not need a whole new website
Decide whether to improve what you have or start again.
When a website becomes frustrating, replacing it can sound like a relief. You could finally fix everything at once.
Before committing, write down the problems you want to solve. "It feels old" is a starting reaction. "We cannot update our services without asking for help" gives you something specific to investigate.
Separate appearance from everyday problems
Perhaps you dislike the colours, but customers can find what they need and your team can update the pages. A smaller visual refresh may be enough.
Or the site looks fine, but enquiries go to the wrong place and product information is difficult to maintain. Those problems call for a closer look at how it is managed.
Ask what you can keep
Useful content and good photography may still have a place. Ask a developer which problems can be fixed within the current site, which need larger changes, and what the tradeoffs are.
Include the time your team needs to supply content and review work. Judge the proposal against the problems you wrote down, so you can tell what your investment is meant to change.
Fix something you can evaluate
If you are unsure how much work is needed, choose one problem that can be addressed on its own. That might be an unclear service page or a product update that currently takes too long.
Agree on what the smaller piece of work includes and what you want to learn from it. Ask your team whether the update is easier to manage and check the page as a customer would.
If the underlying site keeps preventing straightforward changes, you have a more concrete reason to discuss a rebuild. Keep that finding in the project brief so the new site is judged against the problem that prompted it.

