Smart phone USB-C Data and Power
USB-A-to-USB-C cables are a bit silly: The resistor which denotes power draw is in the cable itself.
Thus you only need to buy some USB-A-to-C cables of Amazon (or any other retailer), all 3 resistor values are available AFAIK (equivalent to 500mA, 1.5A, 3A).
Sounds like the vendor packaged a 500mA cable with the phone. Correct according to USB spec, but most PCs allow 1.5A current draw without damaging anything.