(L&LD, Magic, indeed. I believe in Magic, as released in '65 by the Lovin Spoonful.
vpn4, you could always try to ask Merlin for the secrets to the magic DNS sauce
Rather than messaging Express, you might try to restate your issue to company management. Without a better description of your configuration and systems setup, it's not likely Express is the cause of the DNS leaks you're experiencing. Anything's possible but they'd know if they were leaking. If you're using the Express app or client configs, they'd know if that was causing. Your post opens the deep, dark VPN rabbit-hole.
Most VPNs are sensitive to their customer's issues, but have no control over router, system or device configuration problems which are where most DNS leaks originate (browser also contribute to leaks). VPNs want to protect their company infrastructure and customer's bits and bytes. If a provider mishandles customer's traffic, they'll lose those customers, hardly in their or their customer's best interests. Mitnick wannabes, script kiddies and the ever-growing legions of hostile state hackers and common crooks have always loved misusing the same VPNs everyone else now uses, only they still like paying with stolen financial data, an old story. There aren't as many quality, verifiable domestic VPN providers in free countries as there once were; none exit in Putin's Russia or in their best friends list, nor in red china or other like-minded controlled states, where all VPNs are outlawed. Detection of any attempted use of non-state controlled VPN apps have resulted in quite a few arrests and disappearances.
In many countries state agents present security letters or warrants to a VPN owner, along with an gag order never to reveal their plight. Regardless of countless promises made by all VPNs to their customers, to end or relocate their business rather than compromise customer's privacy, never monitoring traffic, etc, VPNs aren't a silver bullet. No owner will risk immediate arrest and imprisonment, with an indefinite cramped prison lifestyle, camping with a new large, lonely cellmate. Customers may not learn of an incident for many years, if ever. The other VPNs you mention have their fans and a decent reputation. Any service advertising world-wide virtual servers is questionable so perform research before you really leave Express. It's difficult to locate most VPN's CEOs (they like their privacy too, even the legitimate guys), in order to sent them a proper letter to further explain your issues.
Your situation seems complicated, but remain thankful you're not trying to exist in Venezuela. Their electrical grid failed catastrophically two weeks ago with no power, internet or other forms of communications services. No fuel is reaching the population, though a few news outlets are risking their sat-phones driving around to uplink video recorded by non-transmitting smart-phones (no cell service). All their electronics are recharged by their car or a small portable solar panel, and no adequate sanitary conditions exist anywhere. Except for the small amount of food and water the news folk bring in with them for their needs, no food, water, medicine, hospital or other medical services are available. An active war zone elsewhere isn't equal to the instant devastation that a complete power grid collapse brings to an otherwise modern country. An EMP attack as depicted in the novel, 'One Second After' would be the only way short of nuclear war, to send a 21st century country back to the dark ages, with the same amount of anarchy. Not a rant, and best of luck resolving your DNS leaks.