I agreed a 3 month period of work with my client for $1000. She was hesitant so I said she could pay in 2 instalments and she did pay the first $500. Now I have requested that she fulfill the next part of the payment as I complete redesigned the campaigns midway and now I have had no responses to emails, whatsapps or messages on this portal.
What can I do? Can I set up the second milestone? Or just request payment another way?
If the milestone is funded you just request the payment via the contract.
If the milestone was not funded you can not do a single thing, which is why we are reminding each other many, many times a day NEVER to do any more work on an unfunded milestone than we are happy to not get paid for, ever....
Many of us do it for trusted, long term clients, but sooner or later it'll go wrong for many, if not most.
I would certainly not do $ 500 worth without funding.
Unfortunately, the second Milestone which was suppose to cover the second part of the work and payment wasn't created. Since Escrow wasn't funded, you'll need to communicate with your client directly regarding issuing a payment for the remaining funds, for the work you already delivered. Before accepting an offer, make sure Escrow is funded for the agreed amount or at least for the initial Milestone. Once delivered, you need to wait for the client to create and fund a second Milestone before continuing to work on their contract.
You can find more information about the way payments are processed on Fixed-Price contracts and Upwork's Payment Protection in this Help article.