the irs referral form 3949-A. you can contact the GP/mamaging member and tell them you are filing a referral form with the iRS for failure to provide the k-1 as required by law. if you are correct the IRS can impose severe penalties on those responsible for the failure.
https://www.irs.gov/pub/irs-pdf/f3949a.pdf
your problem is if you don't get the k-1 what to do on your return.
you can estimate the results and file form 8082 (see the instructions as to who can file) to notify the iRS that what you are reporting may not be correct. This may relieve you of certain penalties if you underestimate your tax liability.
https://www.irs.gov/pub/irs-pdf/f8082.pdf
https://www.irs.gov/pub/irs-pdf/i8082.pdf
your other option is to wait for the k-1, ie file late if needed, but penalties may be impose if you end up owing taxes.
