Option 1 -> Grammatically incomplete; "not have" cannot stand alone without an auxiliary verb.
Option 2 -> Incomplete structure; "haven't" requires a past participle to follow it in this context.
Option 3 -> Present perfect tense (haven't had) correctly indicates an action continuing from the past to the present, matching "so far."
Option 4 -> Past perfect tense refers to a time before another past event, but "so far" indicates up to the present moment.
Hence, Option 3: haven't had -> The phrase "so far" is a clear indicator that the present perfect tense is needed, as it describes a time period extending from the past up until now. The structure "haven't had" (have + past participle) properly expresses that no problems have occurred during this ongoing timeframe. -> correct