How to Convert 3-Phase Power to Single-Phase for Higher Current Devices?

Hello,
At the construction site, I have a 3-phase connection with a relatively low connection power. This is simply the contract I have with the energy company. The protection in the connector is 10A (three-pole). Sometimes I need to connect a single-phase device with a higher power of 2-3 kW and the protection trips.
Is it possible to somehow connect 3 phases in parallel to obtain 1 phase with higher current efficiency? I know that this cannot be done directly (there would, of course, be a phase-to-phase short circuit). But are there any devices, converters or perhaps other solutions that are used to shift the phases so that they can be directly connected?
One idea is to use a 3-phase bridge and a DC to sine converter, but this solution is quite expensive.
Is there any other simple and cheap way?

Factory solutions cost approximately PLN 1,000 to PLN 2,000, i.e. a frequency converter with a 3-phase output and a 1-phase output (or 3 phases but with a load capacity of approximately 25A) and the second output should be equipped with a transformer of appropriate power.

By how much will the current efficiency at the output of the 400/230V transformer increase with this solution? I connect the primary winding between two phases (phase-to-phase voltage 400VAC) protected by a 10A fuse each. How much current will be able to flow through the secondary winding? ~17A ?

Practically, with 2 phases you have 400*10 = 4000 W.

...i.e. on the secondary 4000 W / 230 V = ~17A. The cost of such a transformer is also considerable - PLN 700-800

It will be cheaper to increase the connection power and there will be fewer problems in the future.

Increase the connection power.
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